This invention relates to a conveyance system for a conveyor assembly constructed by arranging a plurality motorized rollers used for so-called goods conveyance for, e.g., loading and unloading parts in an automated warehouse or sorting postal matters.
A roller conveying apparatus (conveyor assembly) in which a multitude of motors and motorized rollers having a built-in speed reducer are arranged along an entire conveyance path with free rollers provided therebetween such that their longitudinal directions are normal to a direction of goods conveyance is known. The motorized roller used in such a conveyor assembly gives a conveying force to an item on a rotary drum by driving a motor in the rotary drum in the form of a roller and transmitting a rotational force to the rotary drum at the outer side via the speed reducer.
In recent years, a multitude of branch paths are provided to cope with a plurality of joint paths or a multitude of sorting ends by extending the lengths of conveyors in a roller conveyor assembly and the like for, e.g., sorting postal matters. However, if an increased number of motorized rollers are used as the length of the conveyor assembly is extended, power consumed is not negligible if the respective motorized rollers are constantly rotated. Accordingly, a conveyance controller constructed by a computer or the like has been recently used to drive the motorized rollers only while the goods are being conveyed by detecting the presence or absence of the goods, thereby centrally executing conveyance control for the purpose of power saving.
However, in order to execute the highly efficient conveyance control described above, a multitude of sensors for detecting the presence or absence of the goods need to be so provided as to correspond to the respective motorized rollers. Thus, the number and length of wires provided between the conveyance controller and the respective parts including wires for transmitting drive signals to the respective motorized rollers and wires between the respective sensors become huge. Particularly, in positions near the conveyance controller, bundles of wires become thick, which necessitates a construction of the conveyor assembly considering a space for such thick bundles of wires and a wiring construction. Further, since the number of the wires is huge, an unnecessarily long time is needed for the diagnosis and inspection at the time of a mechanical trouble, maintenance, etc.
It is an object of the present invention to provide a conveyance system which is free from the problems residing in the prior art.
According to an aspect of the invention, a conveyance system is provided with a conveyor assembly including a first conveyor unit and a second conveyor unit arranged after the first conveyor unit. Each conveyor unit is provided with a plurality of motorized rollers. Each motorized roller has a rotary drum and a motor for rotating the rotary drum. There are provided a plurality of free rollers between two adjacent motorized rollers. The motorized rollers are driven to convey items from the first conveyor unit to the second conveyor unit.
The conveyance system is further provided with a conveyance controller having a communication master function, a sensor at a position corresponding to each of the plurality of motorized rollers in each of the first and second conveyor units for detecting presence or absence of an item, a first communication slave unit in a position corresponding to the first conveyor unit and be able to communicate with the conveyance controller in serial transmission, a second communication slave unit in a position corresponding to the second conveyor unit and be able to communicate with conveyance controller in serial transmission, and a transmitting/receiving device for rendering communications between each sensor and the corresponding communication slave unit and communications between each motorized roller and the corresponding communication slave unit to transmit a drive signal for the corresponding motorized roller to the corresponding communication slave unit and receive a detection signal of the corresponding sensor.
The conveyance controller includes a receiver for cyclically receiving respective detection signals of the sensors via the first and second communication slave units, a command data generator for generating operation command data to rotate or stop relating motorized rollers in response to the detection signals from the sensors received by the receiver, and a transmitter for cyclically transmitting generated operation command data to the first and second communication slave units in serial transmission.
These and other objects, features and advantages of the present invention will become more apparent upon a reading of the following detailed description and accompanying drawings.